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EvoGameTheorySim.cs
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EvoGameTheorySim.cs
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using System;
using System.Collections.Generic;
using Godot;
using PrimerTools;
using System.Linq;
using PrimerTools.Graph;
using EntityID = System.Int32;
using ParentID = System.Int32;
using StrategyID = System.Int32;
[Tool]
public partial class EvoGameTheorySim : Node
{
#region Running toggle
private bool _run = true;
[Export]
private bool Run
{
get => _run;
set
{
var oldRun = _run;
_run = value;
if (_run && !oldRun && Engine.IsEditorHint())
{
// Avoids running on build
RunSim();
PrintResults();
}
}
}
#endregion
public void RunSim()
{
Initialize();
Simulate();
}
#region Entity Registry
public EntityRegistry Registry = new();
public class EntityRegistry
{
private EntityID _nextId;
public readonly List<StrategyID[]> Strategies = new();
public readonly List<ParentID> Parents = new();
public EntityID CreateBlob(StrategyID[] strategy, EntityID parent)
{
var id = _nextId++;
Strategies.Add(strategy);
Parents.Add(parent);
return id;
}
}
#endregion
public class RPSGame
{
public RPSGame(float winMagnitude, float tieCost)
{
this.winMagnitude = winMagnitude;
this.tieCost = tieCost;
}
public RPSGame()
{
GD.PushWarning("Creating default RPSGame.");
}
public enum Strategy
{
Rock,
Paper,
Scissors
}
public readonly Strategy[] StrategyOptions = Enum.GetValues<Strategy>();
public (float reward1, float reward2) GetRewards(int strategy1, int strategy2)
{
return (
RewardMatrix[strategy1, strategy2] + RewardModifiers[strategy1, strategy2] - GlobalCost,
RewardMatrix[strategy2, strategy1] + RewardModifiers[strategy2, strategy1] - GlobalCost
);
}
private const float GlobalCost = 0.0f;
private readonly float winMagnitude = 1f;
private readonly float tieCost = 0.0f;
public float[,] RewardModifiers => new float[3, 3]
{
{ 0, 0, 0 },
{ 0, 0, 0 },
{ 0, 0, 0 }
};
private float[,] RewardMatrix => new float[3, 3]
{
{ 1 - tieCost, 1 - winMagnitude, 1 + 1 * winMagnitude }, // Rock rewards
{ 1 + winMagnitude, 1 - tieCost, 1 - winMagnitude }, // Paper rewards
{ 1 - winMagnitude, 1 + winMagnitude, 1 - tieCost } // Scissors rewards
};
}
#region Parameters
private Rng _rng;
[Export] public int Seed = -1;
public int NumDays = 20;
public int InitialBlobCount = 32;
public int NumTrees = 50;
public float MutationRate = 0;
public bool InitializeByAlleleFrequency = true;
public float[] InitialAlleleFrequencies;
public Dictionary<int[], float> InitialMixedStrategyDistribution;
public int NumAllelesPerBlob = 1;
#endregion
#region Simulation
public List<EntityID>[] EntitiesByDay; // = new List<EntityID>[21];
public List<EntityID>[] ShuffledParents;
public RPSGame RpsGame;
private void Initialize()
{
_rng = new Rng(Seed == -1 ? System.Environment.TickCount : Seed);
RpsGame ??= new RPSGame();
EntitiesByDay = new List<EntityID>[NumDays + 1];
if (InitializeByAlleleFrequency)
{
// Check for valid initial frequencies
if (InitialAlleleFrequencies is not { Length: 3 })
{
GD.PushWarning("No valid initial frequencies defined. Using even distribution.");
InitialAlleleFrequencies = new[] { 1 / 3f, 1 / 3f, 1 / 3f };
}
// Normalize
var sum = InitialAlleleFrequencies.Sum();
if (Mathf.Abs(sum - 1) > 0.001f) GD.PushWarning("Initial allele frequencies don't add to 1. Normalizing.");
InitialAlleleFrequencies = InitialAlleleFrequencies.Select(x => x / sum).ToArray();
var initialAlleleCounts =
InitialAlleleFrequencies.Select(
x => Mathf.RoundToInt(x * InitialBlobCount * NumAllelesPerBlob)
).ToArray();
var blobIDs = new List<EntityID>();
for (var i = 0; i < InitialBlobCount; i++)
{
// Figure out the strategy alleles
var strategyAlleles = new int[NumAllelesPerBlob];
for (var j = 0; j < NumAllelesPerBlob; j++)
{
// First, choose an allele type at random
var stratIndex = _rng.RangeInt(3);
// If there are alleles left to pass out, make sure we picked a type that remains
if (initialAlleleCounts.Sum() > 0)
{
while (initialAlleleCounts[stratIndex] == 0)
{
stratIndex = _rng.RangeInt(3);
}
}
// Assign the allele and decrement the number remaining of that allele
strategyAlleles[j] = stratIndex;
initialAlleleCounts[stratIndex] -= 1;
}
// Create the blob and assign the strategy alleles
blobIDs.Add(Registry.CreateBlob(
strategyAlleles,
-1
));
}
EntitiesByDay[0] = blobIDs;
}
else
{
// Check that initial strategy distribution is valid
var sum = 0f;
foreach (var pair in InitialMixedStrategyDistribution)
{
sum += pair.Value;
if (pair.Key.Sum() != NumAllelesPerBlob)
{
GD.PrintErr($"{string.Join(", ", pair.Key)} is not a valid mixed strategy, since there should be {NumAllelesPerBlob} alleles per blob.");
}
if (pair.Key.Length != RpsGame.StrategyOptions.Length)
{
GD.PrintErr($"{string.Join(", ", pair.Key)} is not a valid mixed strategy. There should be {RpsGame.StrategyOptions.Length} strategies specified.");
}
}
var normalizedInitialMixedStrategyDistribution =
InitialMixedStrategyDistribution.ToDictionary(pair => pair.Key, pair => pair.Value / sum);
// Normalize it
var blobIDs = new List<EntityID>();
foreach (var pair in normalizedInitialMixedStrategyDistribution)
{
GD.Print($"{pair.Key[0]}, {pair.Key[1]}, {pair.Key[2]}");
var listOfIndividualStrategies = new List<int>();
var stratIndex = 0;
foreach (var alleleCount in pair.Key)
{
listOfIndividualStrategies.AddRange(Enumerable.Repeat(stratIndex, alleleCount));
stratIndex++;
}
for (var i = 0; i < Mathf.CeilToInt(pair.Value * InitialBlobCount); i++)
{
blobIDs.Add(
Registry.CreateBlob(
listOfIndividualStrategies.ToArray(),
-1
)
);
}
}
EntitiesByDay[0] = blobIDs;
}
}
private void Simulate()
{
for (var i = 1; i <= NumDays; i++)
{
// Parents are already shuffled, since they were shuffled at the end of the last iteration of the loop
var shuffledParents = EntitiesByDay[i - 1];
var numGames = shuffledParents.Count - NumTrees;
numGames = Mathf.Max(numGames, 0);
numGames = Mathf.Min(numGames, NumTrees);
var dailyChildren = new List<EntityID>();
for (var j = 0; j < numGames * 2; j += 2)
{
var parent1Strategy = Registry.Strategies[shuffledParents[j]];
var parent2Strategy = Registry.Strategies[shuffledParents[j + 1]];
var (reward1, reward2) =
RpsGame.GetRewards(parent1Strategy.RandomItem(_rng), parent2Strategy.RandomItem(_rng));
for (var k = 0; k < GetOffspringCount(reward1); k++)
{
dailyChildren.Add(Reproduce(shuffledParents[j], parent1Strategy));
}
for (var k = 0; k < GetOffspringCount(reward2); k++)
{
dailyChildren.Add(Reproduce(shuffledParents[j + 1], parent2Strategy));
}
}
for (var j = numGames * 2; j < shuffledParents.Count; j += 1)
{
if (numGames < NumTrees)
{
var parentStrategy = Registry.Strategies[shuffledParents[j]];
dailyChildren.Add(Reproduce(shuffledParents[j], parentStrategy));
dailyChildren.Add(Reproduce(shuffledParents[j], parentStrategy));
}
// Else they die, which is just not reproducing, so do nothing
}
// Shuffle at the end of the loop so entities are sorted by tree for the next day
EntitiesByDay[i] = dailyChildren.ShuffleToList(rng: _rng);
}
}
private int Reproduce(int parentIndex, int[] strategies)
{
// TODO: Make mutations work for an arbitrary number of possible strategies
// instead of just 3
// Make a copy
var childStrategies = strategies.ToArray();
// Mutations
for (var i = 0; i < childStrategies.Length; i++)
{
var roll = _rng.RangeFloat(1);
if (roll < MutationRate / 2)
{
childStrategies[i] = (childStrategies[i] + 1) % RpsGame.StrategyOptions.Length;
}
else if (roll < MutationRate)
{
childStrategies[i] = (childStrategies[i] + 2) % RpsGame.StrategyOptions.Length;
}
}
return Registry.CreateBlob(
childStrategies,
parentIndex
);
}
private int GetOffspringCount(float reward)
{
var offspringCount = 0;
var wholeReward = Mathf.FloorToInt(reward);
var fractionReward = reward - wholeReward;
for (var j = 0; j < wholeReward; j++)
{
offspringCount++;
}
if (_rng.RangeFloat(1) < fractionReward)
{
offspringCount++;
}
return offspringCount;
}
#endregion
private void PrintResults()
{
foreach (var (day, frequencies) in GetStrategyFrequenciesByDay().WithIndex())
{
GD.Print($"Day {day}");
GD.Print($"Rock: {frequencies[0]:P1}, Paper: {frequencies[1]:P1}, Scissors: {frequencies[2]:P1}");
}
}
public Vector3[] GetStrategyFrequenciesByDay()
{
var frequencies = new Vector3[NumDays + 1];
foreach (var (day, entitiesToday) in EntitiesByDay.WithIndex())
{
var numAllelesToday = entitiesToday.Count * NumAllelesPerBlob;
var fractionRock = (float) entitiesToday.Sum(s => Registry.Strategies[s].Count(x => x == 0)) / numAllelesToday;
var fractionPaper = (float) entitiesToday.Sum(s => Registry.Strategies[s].Count(x => x == 1)) / numAllelesToday;
var fractionScissors = (float) entitiesToday.Sum(s => Registry.Strategies[s].Count(x => x == 2)) / numAllelesToday;
frequencies[day] = new Vector3(fractionRock, fractionPaper, fractionScissors);
}
return frequencies;
}
public List<List<float>> GetMixedStrategyFreqenciesByDay()
{
var frequenciesByDay = new List<List<float>>();
foreach (var (day, entitiesToday) in EntitiesByDay.WithIndex())
{
var frequenciesToday = new List<float>();
// i and j are the number of increments toward paper and scissors, respectively
for (var i = 0; i <= NumAllelesPerBlob + 1; i++)
{
for (var j = 0; j < NumAllelesPerBlob + 1; j++)
{
if (j + i >= NumAllelesPerBlob + 1) continue;
frequenciesToday.Add((float)entitiesToday.Count(
x =>
Registry.Strategies[x].Count(y => y == 1) == i
&& Registry.Strategies[x].Count(y => y == 2) == j)
/ entitiesToday.Count);
}
}
frequenciesByDay.Add(frequenciesToday);
}
return frequenciesByDay;
}
}